A student focussed the image of a candle flame on a white screen
using a convex lens. He noted down the position of the candle
screen and the lens as under
Position of candle = 12.0 cm
Position of convex lens = 50.0 cm
Position of the screen = 88.0 cm
(i) What is the focal length of the convex lens?
(ii) Where will the image be formed if he shifts the candle towards
the lens at a position of 31.0 cm?
(iii) What will be the nature of the image formed if he further shifts
the candle towards the lens?
(iv) Draw a ray diagram to show the formation of the image in case
(iii) as said above.
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A student focused the image of a candle flame on a white screen using a convex lens. He noted down the positions of the candle flame, screen and the lens as given below:
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asked Jun 13, 2018 in Class X Science by aditya23 (-2,145 points)
A student focused the image of a candle flame on a white screen using a convex lens. He noted down the positions of the candle flame, screen and the lens as given below:
Position of the candle flame = 12.0cm
Position of the lens= 50.0 cm
Position of the screen=88.0 cm
(i) the focal length of the convex lens.
(ii) Find the position of the image of the candle flame if it is shifted towards the lens at a position of 31.0 cm.
(iii) State the nature of the image formed if the candle flame is further shifted towards the lens.(i) object distance u = position of convex lens - position of candle
U = -(50 -12) = -38 cm
image distance v = position of screen -position of convex lens
V-88-50 cm
v- 38 cm
Applying the lens formula:
On calculating focal length will be f-19 cm
(ii) When the candle is shifted towards the lens at a position of 31.0 cm:
Object distance u--(50-31)
U = -19 cm
Applying the lens formula
Therefore, v is infinity
(iii). If the candle is further shifted towards the lens, then the nature of the image formed will be virtual, erect and magnified
(iv) The ray diagram will be as follows: